1、 Overview: A powerful tool for “spatial reconstruction” in old urban areas
Completely feasible. In residential buildings and Ruko (shophouses) on floors 1-3 in Indonesia, using synchronous hydraulic jacking technology to lift the entire house and insert a new floor below is a very mature high-end engineering technology. Especially in areas with low-lying terrain, susceptibility to flood threats, or severe ground subsidence (such as North Jakarta, Semarang, Surabaya), the popularity of this program is increasing year by year.
2、 Compared to adding layers upwards, the core advantage of adding layers upwards and downwards is the lifting of the top
⑴. “Zero load” of foundation and structure:
Adding layers upwards is to stack on top of the old skeleton, while adding layers downwards is to replace the old house with a ‘new skeleton’. The new floor has an independent foundation (usually a micropile) and frame, and the existing old house only acts as a “load” on top of the new structure, without adding any burden to the original structure.
⑵ Solve waterlogging and subsidence:
Many houses in Jakarta have fallen below the road surface due to ground subsidence, and are prone to flooding during the rainy season. During the expansion of the building, the top lift and additional floors raise the house above the flood warning line, completely solving the problem of flooding.
⑶ Synchronize “straightening” correction:
Houses in soft soil areas are often inclined. The lifting system can achieve asymmetric lifting and automatically complete leveling during the process of adding floors, allowing the crooked house to regain verticality.
⑷ Doubling commercial value:
The rent and commercial value of the bottom floor are much higher than those of the top floor. Raising the house and inserting a tall hall or shop on the ground floor can result in a very high return on investment (ROI).
3、 Safety measures for the entire construction process
In Indonesia, a high-intensity earthquake zone and soft soil environment, safety control must be achieved at the millimeter level
⑴ Early stage: Precision identification and environmental assessment
Geological exploration (Sondir Test): It is necessary to determine the depth of soft soil. If there is a thick peat layer below, foundation grouting and solidification must be carried out first.
Ring Balk Replacement: To prevent the house from falling apart during lifting, a highly rigid temporary reinforced concrete beam system must be constructed at the bottom of the house.
⑵ Mid term: Synchronous control and earthquake prevention (most critical)
Synchronous hydraulic system: Adopting PLC computer-controlled synchronous lifting equipment to ensure that the error of the lifting point is controlled within 0.5mm.
Seismic Locking: Indonesia experiences frequent aftershocks. At each stage of lifting (usually 20-50cm), temporary steel structure support must be immediately implanted and locked. It is strictly prohibited for the house to be suspended overnight on the hydraulic cylinder for a long time.
Flexible connection: Indoor water pipes and wires must be replaced with temporary flexible hoses to ensure continuous water supply, uninterrupted power supply, and no wire breakage during the lifting process.
⑶ Later stage: Perfect integration of old and new systems
Deep foundation implantation: The new layer of foundation must penetrate the soft soil layer into the bearing layer to ensure that the newly added layer will not experience further settlement in the future.
Seismic joint treatment: Energy dissipation and shock absorption pads should be installed at the connection between new and old structures in accordance with SNI 1726:2019 to prevent collisions during earthquakes.
4、 Legal compliance and cultural coordination
Approval path (PBG&SLF): The addition of floors to the roof belongs to the category of “Renovasi Total”. A new structural verification report must be submitted to the local government to apply for PBG. Due to the improved building safety of this technology, it is usually easier to obtain approval from the Expert Review Board (TABG) than blindly adding floors upwards.
Community Communication (RT/RW):
The lifting project looks grand and can easily cause panic among neighbors.
Expert reminder: Before construction, it is necessary to invite the RT/RW team leader to inspect the equipment, demonstrate synchronous control technology, and prove that the construction will not vibrate neighboring houses.
Cultural etiquette: According to Indonesian customs, a simple Slametan (blessing ceremony) can be held before starting work, which helps reduce neighborhood resistance.
5、 Suggestions for scheme decision-making
Project indicators: Top up, bottom layer added, traditional top layer added
High basic security (newly established independent foundation) and high risk (relying on old foundation)
Directly solving flood control and waterlogging without improvement
High construction difficulty (requires a professional team)
The estimated cost (IDR) is relatively high (requiring precision machinery) and relatively low
Significant asset appreciation (underlying commercialization), generally
6、 Summary
Top up and bottom layer addition is not only feasible in Indonesia, but also the optimal technical path for increasing the value of old properties and reducing disaster damage.
Core guarantee: Non synchronous lifting operations are strictly prohibited (which may lead to collapse).
Full house crack monitoring must be completed before lifting.
Expert advice:
If you are operating such projects in the northern or coastal areas of Jakarta, please be sure to consider the long-term impact of seawater backflow (Rob). The lifting height should refer to the predicted water level for the next 20 years provided by the local public works bureau (Dinas PU) to ensure a one-time solution to the hidden problem of flooding.